This invention relates to logging a well substantially as soon as its borehole is drilled. More particularly, the invention relates to drilling a well with a signal-transmissive drill string containing a movably mounted magnitude-responsive transducer, moving that transducer against the borehole wall, raising the drill string while logging properties which are so encountered, then returning the transducer within the external confines of the drill string before the drill string is lowered or removed from the borehole of the well.
The existence of a long-felt need for a means for reliably transmitting electrical signals along a drill string is described in the L. L. Dickson and E. G. Ward U.S. Pat. No. 3,696,332. The patent references numerous prior proposals and describes an improved system that uses an insulated electrical conductor which extends along some or all of the pipe joints of a segmented drill string assembly. An E. B. Denison U.S. Pat. No. 4,126,848, describes particularly suitable embodiments of signal-transmissive drill string assemblies which contain wire lines for transmitting electrical signals from near bottom to intermediate locations and either insulated wire-containing pipe sections or electromagnetic signal-transmitting and receiving means for transmitting electrical signals to and from a sufrace location. A copending patent application by C. B. Vogel and G. T. Worell, Ser. No. 819,806, filed July 28, 1977, now U.S. Pat. No. 4,130,816 relates to a circumferential acoustical detector involving a plurality of cylindrical transducers mounted on movable arms with means for moving them into and out of close proximity with a borehole wall in order to provide an acoustic log capable of detecting the presence of vertical fractures. The disclosures and references contained in the U.S. Pat. Nos. 3,696,332, 4,126,848 and 4,130,816 patents are incorporated herein by reference.